Hybrid magnetic structure and method for producing the same

Abstract: According to the present invention, a hybrid magnetic substrate is provided, which includes: a magnetic substrate; and a holding substrate directly bonded to the magnetic substrate through at least one of a hydrogen bond and a covalent bond. Furthermore, a method for producing a hybrid magnetic substrate having the magnetic substrate and the holding substrate is provided, which includes the steps of: cleaning a surface of the magnetic substrate to be bonded and a surface of the holding substrate to be bonded; allowing the cleaned surfaces to be subjected to a hydrophilic treatment; and attaching the surfaces, which are subjected to the hydrophilic treatment, to each other to directly bond the magnetic substrate to the holding substrate.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention: The present invention relates to a hybrid magnetic structure and a method for producing the same. In particular, the present invention relates to a hybrid magnetic structure in which a magnetic layer is bonded to a supporting substrate through direct bonding and a method for producing the same. 2. Description of the Related Art: As devices utilizing a magnetic, there are optical isolators allowing light to pass only in a predetermined direction by using a magneto-optic effect and various kinds of magnetostatic wave devices using a magnetostatic wave propagating through a magnetic. In most cases, these devices utilize a magnetic as a magnetic layer on another substrate or as a thin film formed on another substrate. In the present specification, an entire structure composed of a substrate and a magnetic layer or magnetic film layered on the substrate is referred to as a hybrid magnetic structure. For example, Japanese Laid-Open Patent Publication No. 2-232606 discloses a thin film wave guiding type optical isolator having, on a garnet single crystalline substrate, a garnet type thin film as an intermediate layer and another garnet type thin film as a waveguide layer made of a magneto-optic material. This construction is formed by a liquid phase epitaxial method. Figure 1 shows a construction of a conventional optical isolator 201 . In this figure, a substrate 101 is made of, for example, a gadolinium-gallium-garnet (GGG) single crystal. The intermediate layer 104 is formed by a liquid phase epitaxial method. As the intermediate layer 104 , yttrium-iron-garnet (YIG) type materials are used. An optical waveguide layer 102 is formed on the intermediate layer 104 by a liquid phase epitaxial method. As the optical waveguide layer 102 , YIG type materials are also used. On the optical waveguide layer 102 , an upper layer 103 is formed. As a material for the upper layer 103 , ZnO is used, for example. The upper layer 103 is not indispensable. Instead of forming the upper layer 103 , the upper face of the optical waveguide layer 102 may be exposed. Light is confined in the optical waveguide layer 102 by providing the intermediate layer 104 having a refractive index smaller than that of the optical waveguide layer 102 . Furthermore, the optical waveguide layer 102 is made of a YIG type material having a magneto-optic effect, so that it works as an optical isolator. Regarding magnetostatic wave devices, for example, J. Castera (Journal of Applied Physics, 55(6), pp. 2506-2511, 1984) discloses a method for producing a magnetostatic wave device and various applications of the magnetostatic wave device. This publication describes a method for forming a thin film made of YIG on a GGG substrate by a liquid phase epitaxial method, and exemplifies filters, oscillators, delay lines, etc. as the applications of the magnetostatic wave device. The above-mentioned conventional examples have the following problems: In a method for forming a hybrid magnetic structure by various kinds of epitaxial growth methods, only a film with a lattice constant matching with that of a substrate can be formed, so that the combination of the materials for the film and the substrate is limited. The crystal orientation of the film to be formed depends upon that of the substrate, which decreases the degree of freedom of forming a film having a preferred crystal orientation. Furthermore, even though any of the epitaxial growth methods such as liquid phase epitaxial growth, chemical vapor phase epitaxial growth, and molecular beam epitaxial growth is used, it has been difficult to obtain a magnetic film having characteristics superior to those of a bulk single crystal. For layering substrates made of different materials, methods for fixing them with various kinds of adhesives can be used. Japanese laid-open patent publication No. 1-121 217 discloses such a bonding between a mirror finished glass substrate and a magnetic film through a silane coupling film. However, according to the conventional methods using adhesives, the precision of the thickness of interface layers bonding the respective layers to each other, heat resistance, chemical resistance, and reliability are not sufficient. SUMMARY OF THE INVENTION The hybrid magnetic structure of the invention comprises : a supporting substrate or a supporting substrate having an inorganic thin film of SiO 2 or Si 3 Ni 4 on its contacting surface, a single crystalline magnetic layer or a single crystalline magnetic layer having an inorganic thin film of SiO 2 or Si 3 Ni 4 on the contacting surface ; the substrate and the layer being covalently bonded with optional additional hydrogen bonding, resulting in either a substrate-layer bond structure or a substrate-thin film-layer bond structure. In another embodiment of the invention the material for the magnetic layer is a garnet. In still another embodiment a material for the magnetic layer is mainly yttrium-iron-garnet. In still another embodiment of the invention, the supporting substrate is made of a semiconductor material. In still another embodiment of the invention the semiconductor material is silicon. In still another embodiment of the invention, the semiconductor material is a III-V group semiconductor material. In still another embodiment of the invention, the material for the supporting substrate is glass. In still another embodiment of the invention, the thermal expansion coefficient of the glass is substantially the same as a thermal expansion coefficient of the magnetic layer. In still another embodiment of the invention, the supporting substrate is a light-transmitting substrate having an electro-optic effect. In still another embodiment of the invention, the material for the supporting substrate is magnetic. In still another embodiment of the invention, the material for the magnetic layer is the same as a material for the supporting substrate. According to another aspect of the invention, a method for producing a hybrid magnetic structure, includes the steps of : cleaning a surface of the magnetic layer to be bonded and a surface of the supporting substrate to be bonded ; allowing the cleaned surfaces to be subjected to a hydrophilic treatment ; and attaching the surfaces, which are subjected to the hydrophilic treatment, to each other to directly bond the magnetic layer to the supporting substrate. Alternatively, a method for producing a hybrid magnetic structure, includes the steps of : forming an inorganic thin film on at least one surface to be bonded of the magnetic layer and the supporting substrate ; cleaning a surface of the inorganic thin film and the surface to be bonded on which the inorganic thin film is not formed ; allowing the cleaned surface of the inorganic thin film and the surface to be bonded on which the inorganic thin film is not formed to be subjected to a hydrophilic treatment ; and attaching the surfaces, which are subjected to the hydrophilic treatment, to each other to directly bond the magnetic layer to the supporting substrate. According to still another aspect of the invention, a magnetic wave device includes a hybrid magnetic structure, and an electrode for exciting a magnetostatic wave is provided on the magnetic layer. Alternatively, a magnetic device includes a hybrid magnetic structure, and the magnetic layer has a magneto-optic effect and an optical waveguide is formed on the magnetic layer. Alternatively, a magnetic device comprises a hybrid magnetic structure, and the magnetic layer has a magneto-optic effect and the magnetic layer has a function as an optical isolator. Alternatively, a magnetic device comprises a hybrid magnetic structure, and the supporting substrate is a light-transmitting substrate having an electro-optic effect and an optical device is formed on the light-transmitting substrate. Alternatively, an integrated magnetic device comprises a hybrid magnetic structure, and the supporting substrate is made of a semiconductor material and at least one element selected from the group consisting of an electronic element and an optical element is formed on the supporting substrate. In still another embodiment of the invention, a hybrid magnetic structure, wherein said hydrogen bond is formed between hydroxyl groups, and the covalent bond is obtained by transforming the hydrogen bond and includes an oxygen atom. In still another embodiment of the invention, a method for producing a hybrid magnetic substrate, further comprises the step of heating the structure to a temperature in the range of 100°C to 500°C. Thus, the invention described herein obtains the advantage of providing a thermally, mechanically, and chemically stable hybrid magnetic structure which has a large degree of freedom of the combination of materials for the substrate and the magnetic layer and which is capable of being finely processed, and a method for producing the same. This and other advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying figures. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a view showing a construction of a conventional optical isolator. Figure 2 is a cross-sectional view of a hybrid magnetic structure of Example 1 according to the present invention. Figures 3A through 3C are views schematically showing the principle of direct bonding. Figure 4 is a view showing a construction of an optical isolator of Example 2 according to the present invention. Figure 5 is a view showing a construction of another optical isolator of Example 2 according to the present invention. Figure 6 is a view showing a construction of another optical isolator of Example 2 according to the present invention. Figure 7 is a view showing a construction of a magnetostatic wave device of Example 3 according to the present invention. Figure 8 is a cross-sectional view of a hybrid magnetic structure of Example 4 according to the present invention. Figure 9 is a cross-sectional view of a hybrid magnetic structure of Example 5 according to the present invention. Figure 10 is a view showing a construction of an integrated magnetic device of Example 5 according to the present invention. Figure 11 is a view showing a construction of an integrated magnetic device of Example 6 according to the present invention. Figure 12 is a view showing a construction of a hybrid magnetic structure of Example 7 according to the present invention. Figure 13 is a view showing a construction of an integrated magnetic device of Example 7 according to the present invention. Figure 14 is a cross-sectional view of a hybrid magnetic structure of Example 8 according to the present invention. Figure 15 is a view showing a construction of an optical isolator of Example 8 according to the present invention. Figure 16 is a view showing a construction of a magnetostatic wave device of Example 8 according to the present invention. Figure 17 is a view showing a construction of a hybrid magnetic structure of Example 9 according to the present invention. Figure 18 is a view showing a construction of a hybrid magnetic structure of Example 10 according to the present invention. Figure 19A is a view showing a construction of an integrated magnetic device of Example 11 according to the present invention; and Figure 19B is a cross-sectional view taken along a line X-X' of Figure 19A . Figure 20 is a cross-sectional view of a hybrid magnetic structure of Example 12 according to the present invention. Figure 21 is a flow chart showing the steps of producing a hybrid magnetic structure shown in Figure 2 . Figure 22 is a flow chart showing the steps of producing a hybrid magnetic structure shown in Figure 14 . DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described by way of illustrative examples with reference to the drawings. Example 1 Figure 2 shows a cross-sectional view of a hybrid magnetic structure 202 of Example 1 according to the present invention. The hybrid magnetic structure 202 has a supporting substrate 1 and a magnetic layer 2 which are bonded to each other through direct bonding. In the present specification, a bond formed by hydrogen bonds or covalent bonds without using an adhesive is referred to as "direct bonding". In the direct bonding, hydrogen bonds and covalent bonds may be formed together. Depending upon the materials used for the substrate and the layer, an ion bond can work for bonding the supporting substrate 1 to the magnetic layer 2 . The substrate and the layer are bonded to each other through direct bonding at an atomic level, and particular elements other than hydrogen, oxygen, and elements forming the substrate and the layer are not present on a bonding interface. The direct bonding will be described with reference to Figures 3A through 3C . First, the surfaces of the substrate 1 and the layer 2 are cleaned, subjected to a hydrophilic treatment, and then dipped into pure water. A number of water molecules and hydroxyl groups are adsorbed to the surfaces of the substrate 1 and the layer 2 . Under this condition, the substrate 1 and the layer 2 are attached to each other. An initial bond is conducted therebetween through hydrogen bonds via the water molecules and the hydroxyl groups. Figure 3A schematically shows this state as a representative example. The substrate 1 and the layer 2 bonded to each other are heated under this condition. In the meantime, water or hydrogen are released from the bonding interface, whereby the bond between the substrate 1 and the layer 2 are strengthened. The reason why the bond between the substrate 1 and the layer 2 is strengthened is that hydrogen bonds via water molecules are changed to hydrogen bonds via hydroxyl groups. Figure 3B schematically shows this state as a representative example. This state can be seen most in the case where the bonded substrate 1 and layer 2 are heat-treated at a temperature in the range of 200°C to 500°C. When the temperature for heat treatment is raised, the hydroxyl groups are further condensed and hydrogen is further released. As a result, the covalent bonds via oxygen mainly contribute to the direct bonding to strengthen the bond between the substrate 1 and the layer 2 . Figure 3C shows this state. In the case where silicon is present on the bonding interface, it also promotes the formation of the covalent bonds to strengthen the bond between the substrate 1 and the layer 2 . Figures 3A through 3C schematically show the representative cases, respectively. It is noted that these states are subject to the elements forming the substrate 1 and the layer 2 and the surface states thereof. Hereinafter, the difference between the bond using an adhesive such as an organic substance and the direct bonding of the present example, and effects obtained by producing a hybrid magnetic structure through the direct bonding will be described. In the case of the bond using an adhesive, a layer of the adhesive always remains on the bonding interface. The thickness of the layer of the adhesive is generally about several pm. In the present example, the thickness of a layer of hydroxyl groups adhering to the substrate and the layer by the hydrophilic treatment generally corresponds to about one molecule, so that the distance between the directly bonded substrate and layer is considered to correspond to about several molecules to several atoms. The observation of the bonding interface by a transmission electron microscope (TEM) showed that the thickness of the direct-bonding interface layers were generally about 10 nm or less. It is considered that the direct-bonding interface layer observed by the TEM includes a hydroxyl group layer on the surfaces of the substrate 1 and the layer 2 and a layer of atoms forming the substrate 1 and the magnetic layer 2 which participate in the direct bonding and which are in a state different from a bulk state. In the present specification, the layer which is formed on the bonding interface and is in a state different from a bulk state is referred to as an interface layer. Accordingly, the direct bonding enables the bond between the substrate 1 and the layer 2 with the interface layer having a thickness of 20 nm or less. This results in satisfactorily parallel relationship between the substrate 1 and the layer 2 . In the case of using an adhesive, irrespective of the kind of the adhesive, i.e., organic adhesives and inorganic adhesives such as glass and cement, the thickness of the layer of the adhesive cannot be controlled in the order of an atomic level. As described above, in the hybrid magnetic structure of the present example, the supporting substrate and the magnetic layer are positioned satisfactorily parallel with each other, so that the fine processing of the surface of the hybrid magnetic structure can be performed with high precision. For example, in the case where a magnetostatic wave device is produced, a fine interdigital electrode is required to be formed on the surface of the hybrid magnetic structure. The width of the interdigital electrode should have a precision at a submicron level. Such a interdigital electrode is generally produced by forming an electrode by vacuum deposition and forming a mask by photolithography, followed by etching. In the case where photolithography at a submicron level is performed, when the supporting substrate and magnetic layer are not sufficiently parallel with each other, the substrate and layer are not exposed to light with good precision, making it impossible to obtain satisfactory processing precision. In fine processing steps such as a wet etching step and a dry etching step, in some cases, the hybrid magnetic structure is exposed to acid and various kinds of gases as an etchant and to high temperature. The hybrid magnetic structure produced by using various kinds of adhesives have problems in the chemical resistance and thermal stability of the adhesives. On the other hand, in the hybrid magnetic structure obtained by direct bonding of the present example, other materials are not used for bonding. Therefore, the chemical resistance and thermal stability of the hybrid magnetic structure is determined by those of the materials for forming the hybrid magnetic structure. In general, the materials for the hybrid magnetic structure have chemical resistance and thermal stability superior to those of, adhesives, so that the materials for the hybrid magnetic structure are not likely to be deteriorated during the above-mentioned fine processing steps. In particular, organic adhesives cannot be maintained in a stable state at higher temperatures. Such being the case, if the organic adhesives are used for bonding, the adhesives are thermally deteriorated during the heating steps such as soldering and reflow soldering conducted at about 230°C in the course of the production of a device using the hybrid magnetic structure. Furthermore, in magnetic devices, e.g., magnetostatic wave devices utilizing the characteristics of the substrate surface, the characteristics of the devices are deteriorated by gas generated from the adhesives during the heating steps. According to the present example, the direct bonding will have a strength of tens of Kg/cm 2 by heat treatment at 200°C for about one hour. In the case where reflow soldering is conducted at about 230°C in the course of the production of the device, bonding with high reliability can be obtained by heat treatment for the direct bonding at 230°C or higher. The direct bonding does not use an adhesive, so that the heat treatment temperature for the direct bonding depends upon only the materials for forming the hybrid magnetic structure. The materials used for the hybrid magnetic structure have excellent heat-resistance; therefore, the hybrid magnetic structure will not be deteriorated during the heating steps in the course of the production of the device. Thus, highly reliable bonding can be formed by performing the heat treatment for the direct bonding at a temperature used for the heating steps. Furthermore, other materials are not present on the bonding interface, so that gas is not generated, which adversely affects the characteristics of the device during the heating steps in the course of the production of the device. It should be noted that, depending upon the use of the hybrid magnetic structure, the direct bonding of the present example has strength sufficient for practical uses, even though the heat treatment for strengthening the direct bonding is not performed. In the direct bonding of the present example there is no limit to the combination of the supporting substrate and the magnetic layer as in epitaxial growth; therefore, the combination of substrates and layers made of materials having different elements, crystal structures, crystal orientations, and lattice constants is made possible. This results in a remarkably high degree of freedom of the combination of the materials for the supporting substrate and the magnetic layer constituting the hybrid magnetic structure. Example 2 Hybrid magnetic structures obtained by using the direct bonding can be used for various devices. In the present example, an optical isolator is produced by using the hybrid magnetic structures. An optical isolator 203 shown in Figure 4 has a supporting substrate 1 made of a magnetic substance such as a GGG single crystal and a YIG substrate 2 as a magnetic layer. The supporting substrate 1 is bonded to the YIG layer 2 through direct bonding. YIG which is a ferrimagnetic material has a light transmitting property and a large Faraday effect. Thus, a hybrid magnetic structure using a YIG layer as an optical waveguide, provided with a polarizer (not shown) on the light incident side of the optical waveguide and with an analyzer (not shown) on the light outputting side thereof, works as the optical isolator 203 . Figure 5 shows the construction of the optical isolator 204 utilizing the hybrid magnetic structure and an external magnetic field. A linearly polarized light passed through a polarizer 52 is transmitted through the YIG layer 2 . The YIG layer 2 is applied with an external magnetic field by permanent magnets 6a and 6b . The length of the YIG layer 2 and the intensity of the external magnetic field are regulated so that the polarization plane of the linearly polarized light is rotated by 45 degrees by the Faraday effect while propagating through the YIG layer 2 . In order for the polarization plane of the linearly polarized light to allow the light rotated by 45 degrees to pass therethrough, the analyzer 54 is provided so that its polarization axis forms an angle of 45 degrees with the polarization axis of the polarizer 52 . Light reflected after passing through the analyzer 54 has its polarization plane rotated by 45 degrees while propagating the YIG layer 2 , and the polarization plane becomes perpendicular to the polarization axis of the polarizer 52 . Thus, the reflected light cannot pass through the polarizer 52 . Therefore, the optical isolator 204 allows light to pass therethrough only in a direction indicated by an arrow in Figure 5 . Here, it is noted that an optical isolator utilizing a Cotton-Mouton effect can be produced by applying an external magnetic field in a direction parallel with a light propagating direction. Known methods can be used for applying an external magnetic field. In the constructions of Figure 4 or 5 , since the refractive index of YIG (i.e., 2.22) is higher than that of GGG, light can be confined in the YIG substrate 2 by setting the thickness of the YIG layer 2 to be a value appropriate for transmission in a single mode, e.g., about 5 µm. The YIG layer 2 works as a so-called slab-type optical waveguide. Another optical isolator can be produced by using the hybrid magnetic structure according to the present invention. Figure 6 shows a channel type optical waveguide optical isolator 205 (in this figure, a polarizer and an analyzer are not shown). The channel type optical waveguide optical isolator 205 has a GGG supporting substrate 1 and a YIG magnetic layer 2 which are directly bonded to each other. The YIG magnetic layer 2 has a mount portion 3 . Because of this construction, light is confined in the mount portion 3 , and the mount portion 3 works as a channel type optical waveguide. Example 3 In the present example, a magnetostatic wave device is produced by using the hybrid magnetic structure according to the present invention. A magnetostatic wave device 206 shown in Figure 7 has a GGG single crystalline substrate 1 as a supporting substrate and a YIG single crystalline layer 2 as a magnetic layer. The GGG single crystalline substrate 1 is bonded to the YIG single crystalline layer 2 through direct bonding as described in Example 1. Interdigital electrodes 4 and 5 for applying a high-frequency electric field are formed on the YIG single crystalline layer 2. A magnet 6 for applying an external magnetic field to the YIG single crystalline layer 2 is provided above the interdigital electrodes 4 and 5 . When a high-frequency electric field is applied to the YIG single crystalline layer 2 under the condition that the YIG single crystalline layer 2 is applied with a magnetic field, a magnetostatic wave is excited in and propagated through the YIG single crystalline layer 2 . The magnetostatic wave has properties similar to those of a surface elastic wave excited on a piezoelectric substrate, so that the magnetostatic wave device can be used as a filter and a resonator in the same way as in a surface elastic wave device. The hybrid magnetic structure used in the magnetostatic wave device 206 of the present example is produced by using the direct bonding. Therefore, the supporting substrate and the magnetic layer have a satisfactorily parallel relationship with each other. This makes it possible to form the interdigital electrodes 4 and 5 on the surface of the YIG single crystalline layer 2 by minute processing with precision at a submicron level. The processing precision of the interdigital electrodes 4 and 5 greatly affects the characteristics of the device (e.g., resonance frequency, loss). Thus, the magnetostatic wave device 206 provided with the interdigital electrodes 4 and 5 with high precision has satisfactory characteristics. Furthermore, the magnetostatic wave device 206 is produced without using an adhesive, so that the device also has excellent reliability, such as heat resistance. Example 4 Figure 8 shows the construction of another hybrid magnetic structure 207 according to the present invention. In the present example, a glass substrate 11 is used as a supporting substrate, and a YIG single crystalline layer 2 is used as a magnetic layer. The glass substrate 11 and the YIG single crystalline layer 2 are bonded to each other through direct bonding in the same way as in Example 1. In the case where quartz glass is used as a material for the glass substrate 11 , the refractive index of quartz glass (i.e., about 1.5) is smaller than that of YIG, so that light can be confined in the YIG layer 2 . Thus, an optical isolator can be obtained in the same way as in Example 2 by providing a polarizer and an analyzer (not shown). Furthermore, a magnetostatic wave device can be obtained by utilizing the construction of Example 3 shown in Figure 7 . Example 5 Figure 9 shows the construction of another hybrid magnetic structure 208 according to the present invention. In the present example, a semiconductor substrate 21 made of, for example, Si is used as a supporting substrate, and a YIG single crystalline layer 2 is used as a magnetic layer. The semiconductor substrate 21 and the YIG single crystalline layer 2 are bonded to each other through direct bonding in the same way as in Example 1. The hybrid magnetic structure 208 can be used for producing a magnetostatic wave device by utilizing the construction of Example 3 shown in Figure 7 . Figure 10 shows the construction of an integrated magnetic device 209 , as an application of the present example, in which a magnetic device and an electronic element are integrated. A magnetostatic wave device portion of the integrated magnetic device 209 has an Si substrate 21 , a YIG layer 2 , interdigital electrodes 4 and 5 , and a permanent magnet 6 , all of which work in the same way as in the magnetostatic wave device of Example 3. The integrated magnetic device 209 further has an electronic circuit portion 22 on the Si substrate 21 . An electronic circuit for applying a high-frequency electric field to the interdigital electrodes 4 and 5 is formed on the electronic circuit portion 22 and the interdigital electrodes 4 and 5 are electrically connected to each other, whereby the magnetic device and the electronic element can be integrated. The electric connection (not shown) between the electronic circuit portion 22 and the interdigital electrodes 4 and 5 is performed by various methods such as wire bonding. Alternatively, the electronic circuit portion 22 is connected to the interdigital electrodes 4 and 5 through a wiring formed on the Si substrate 21 . Furthermore, an oscillating circuit is formed on the electronic circuit portion 22 on the Si substrate 21 and a resonator is formed on the YIG layer 2 , whereby an oscillator oscillating at a resonance frequency of the resonator can be constructed. As described above, by using the hybrid magnetic structure obtained by directly bonding the semiconductor substrate to the magnetic layer, an integrated magnetic device in which a magnetic device and an electronic element are integrated can be produced. Example 6 In the present example, a magnetic device has a semiconductor substrate 23 made of a III-V group compound such as GaAs and InP and a YIG layer 2 . On the III-V group compound semiconductor substrate 23 , an optical element such as a semiconductor laser and a photodiode are formed so as to be integrated with the magnetic device. In such an integrated magnetic device 210 shown in Figure 11 , the III-V group compound semiconductor substrate 23 and the YIG layer 2 are bonded to each other through direct bonding. By providing a polarizer and an analyzer (not shown) on the YIG layer 2 , an optical isolator portion 26 is constituted in the same way as in Example 2. Here, it is noted that the polarizer can be omitted if a semiconductor laser emitting a linearly polarized light is used as the optical element. On the III-V group compound semiconductor substrate 23 , an electronic circuit portion and an optical element portion are formed. In the present example, a semiconductor laser 25 is formed in the optical element portion and a semiconductor laser driving circuit 24 is formed in the electronic circuit portion (electrical connection thereof is not shown in the figure). Light emitted from the semiconductor laser 25 controlled by the semiconductor laser driving circuit 24 is transmitted in the air and introduced into the optical isolator portion 26 . The light transmitted through the optical isolator portion 26 is output outside and introduced into an optical fiber 41 or the like. The light emitted from the semiconductor laser 25 is output outside through the optical isolator portion 26 . Therefore, there is no problem that the output light is reflected to the semiconductor laser to adversely affect laser oscillation. The light is transmitted only in a direction indicated by an arrow in the figure. Thus, in the present example, the optical element, the electronic element, and the magnetic device are integrally formed to miniaturize the entire device and to facilitate optical alignment. Furthermore, in order to reduce the optical coupling loss between the semiconductor laser 25 and the optical isolator portion 26 , the semiconductor laser 25 and the optical isolator portion 26 can be positioned so as to be close to each other, and a layer for aligning the refractive index can be provided between the semiconductor laser 25 and the optical isolator portion 26 . Still furthermore, in order to improve light confinement efficiency, a ridge type optical waveguide can be formed on the optical isolator portion 26 . Example 7 Figure 12 shows the construction of still another hybrid magnetic structure 211 according to the present invention. The hybrid magnetic structure 211 has a light-transmitting substrate having an electro-optic effect as a supporting substrate 31 and a YIG single crystalline layer as a magnetic layer 2 . The supporting substrate 31 and the magnetic layer 2 are bonded to each other through direct bonding in the same way as in Example 1. As a material for the supporting substrate 31 , lithium niobate, lithium tantalate, and the like can be used. In the case where the supporting substrate 31 having an electro-optic effect made of lithium niobate is used, an optical isolator can be formed by using a material having a refractive index smaller than that of the magnetic layer 2 for the supporting substrate 31 and providing a polarizer and an analyzer in the same way as in Example 2. In this case, various kinds of optical elements can be formed on the supporting substrate 31 , so that the optical elements and the optical isolator can be integrally formed. Figure 13 shows an integrated magnetic device 212 on which optical elements and a magnetic device are integrally formed. As shown in this figure, an optical waveguide layer 32 is formed on the supporting substrate 31 . The magnetic layer 2 is bonded to a part of the optical waveguide layer 32 through direct bonding. The optical waveguide layer 32 has optical elements 33 such as a light modulator and a light switch and an optical coupling portion 34 optically coupled with a coupling portion 7 of an optical waveguide of the magnetic layer 2 . The optical coupling in the present example can be performed by various methods. For example, the optical waveguide of the magnetic layer 2 is optically coupled with the optical waveguide layer 32 by providing light directional couplers in both of the coupling portion 7 and the optical coupling portion 34 . Because of the above-mentioned construction, various kinds of optical elements can be integrated. For example, a device, in which a light modulator and an optical isolator are integrally formed, can be produced. Furthermore, by utilizing the construction of Example 3 shown in Figure 7 , a magnetostatic wave device can be produced. Example 8 Figure 14 shows the construction of still another hybrid magnetic structure 213 according to the present invention. The hybrid magnetic structure 213 has a supporting substrate 1 (e.g., a GGG magnetic single crystalline substrate), a YIG magnetic single crystalline layer 2 , and an inorganic thin film 8 formed between the supporting substrate 1 and the YIG magnetic single crystalline layer 2 . The inorganic thin film 8 is made of silicon oxide or silicon nitride. The inorganic thin film 8 is formed on the YIG magnetic single crystalline layer 2 by vacuum deposition, sputtering, chemical vapor deposition (CVD), etc. The YIG magnetic single crystalline layer 2 is bonded to the supporting substrate 1 through direct bonding in the same way as in Example 1 at an interface between the inorganic thin film 8 and the supporting substrate 1 . The devices similar to those described in Example 2 or 3 can be produced by appropriately setting the material and the thickness of the inorganic thin film 8 . For example, the refractive index of silicon oxide and silicon nitride is in the range of about 1.4 to about 1.5, so that an optical isolator 214 shown in Figure 15 can be formed in the same way as in Example 2 by using silicon oxide or silicon nitride as a material for the inorganic thin film 8 and appropriately setting the thickness thereof in the range of about 0.1 to 5 µm. In this case, if the thickness of the inorganic thin film 8 is set to be a wavelength or more of light transmitted therethrough, even though the refractive index of the supporting substrate 1 is larger than that of the YIG magnetic single crystalline layer 2 , an optical waveguide can be formed on the YIG magnetic single crystalline layer 2 and the degree of freedom for combining materials is increased compared with the case where the inorganic thin film 8 is not used. In the case where the inorganic thin film 8 is formed by vacuum deposition, sputtering, CVD, etc., the thickness thereof can be controlled with good precision. Therefore, a magnetostatic wave device 215 shown in Figure 16 can be produced using the hybrid magnetic structure 213 in the same way as in Example 3, which requires a satisfactory parallel relationship between the supporting substrate 1 and the YIG magnetic single crystalline layer 2 . Example 9 Figure 17 shows the construction of still another hybrid magnetic structure 216 according to the present invention. The hybrid magnetic structure 216 has a supporting substrate 11 made of glass, a YIG magnetic single crystalline layer 2 , and an inorganic thin film 8 . The inorganic thin film 8 is made of silicon oxide or silicon nitride. The inorganic thin film 8 is formed on the YIG magnetic single crystalline layer 2 by vacuum deposition, sputtering, CVD, etc. in the same way as in Example 8. The YIG magnetic single crystalline layer 2 is bonded to the supporting substrate 11 through direct bonding in the same way as in Example 1 at an interface between the inorganic thin film 8 and the supporting substrate 11 . Even in the case where quartz glass is used for the supporting substrate 11 , an optical isolator or a magnetostatic wave device can be produced using the hybrid magnetic structure 216 by utilizing the construction of Example 8 . Example 10 Figure 18 shows the construction of still another hybrid magnetic structure 217 . The hybrid magnetic structure 217 has a supporting substrate 21 made of a semiconductor such as Si, a YIG magnetic single crystalline layer 2 , and an inorganic thin film 8 . The inorganic thin film 8 is made of silicon oxide or silicon nitride. The inorganic thin film 8 is formed on the YIG magnetic single crystalline layer 2 by vacuum deposition, sputtering, CVD, etc. The YIG magnetic single crystalline layer 2 is bonded to the supporting substrate 21 through direct bonding in the same way as in Example 1 at an interface between the inorganic thin film 8 and the supporting substrate 21 . Even in the case where a semiconductor is used for the supporting substrate 21 , an optical isolator or a magnetostatic wave device can be produced by utilizing the construction of Example 8 . Furthermore, even when using a semiconductor for the supporting substrate 21 , an integrated magnetic device can be produced in the same way as in Example 5. Example 11 In the present example, a magnetic device has a substrate 23 made of a III-V group compound such as GaAs and InP and a YIG magnetic single crystalline layer 2 . Optical elements such as a semiconductor laser and a photodiode are formed on the semiconductor substrate 23 so as to be integrated with the magnetic device. Hereinafter, an integrated magnetic device 218 with the above-mentioned construction will be described in more detail with reference to Figures 19A and 19B . Figures 19A and 19B are a perspective view of the integrated magnetic device 218 and a cross-sectional view thereof taken along an X-X' line of Figure 19A , respectively. The integrated magnetic device 218 has the semiconductor substrate 23 and the YIG magnetic single crystalline layer 2 . In the present example, the semiconductor substrate 23 is bonded to the YIG magnetic single crystalline layer 2 through direct bonding via an inorganic thin film 8 formed therebetween. On the semiconductor substrate 23 , an electronic circuit portion 24 is formed, and a semiconductor laser 25 ' and an optical waveguide portion 27 are formed in the semiconductor substrate 23 . In the electronic circuit portion 24 , a semiconductor laser driving circuit is formed (electrical connection thereof is not shown in the figure). The YIG magnetic single crystalline layer 2 has an isolator portion 26 and an optical coupling portion 28 . By using the semiconductor laser 25 emitting linearly polarized light and providing an analyzer (not shown) on the light outputting side of the YIG magnetic single crystalline layer 2 , the isolator portion 26 works as an isolator. In the case of using the semiconductor laser 25' which does not emit linearly polarized light, a polarizer may be provided on the light emitting side of the semiconductor laser 25' or in an optical path extending from the light emitting side of the semiconductor laser 25' to the optical coupling portion 28 . The operation of the optical coupling portion 28 of the present example will be described with reference to Figure 19B . The optical waveguide portion 27 provided in the semiconductor substrate 23 is optically coupled with the YIG magnetic single crystalline layer 2 working as an optical waveguide by forming a thin film 8 having refractive index smaller than any of those of the semiconductor substrate 23 and the YIG magnetic single crystalline layer 2 . The thickness of the thin film 8 is in the order of microns or less. Light propagating through the optical waveguide portion 27 is introduced into the optical coupling portion 28 after the propagation of a certain distance. The principle of this optical coupling is the same as that of an optical waveguide directional coupler for coupling optical waveguides positioned on the identical plane. The refractive index of III-V group semiconductors such as GaAs and InP and that of a magnetic substance such as YIG are 2 or higher, and the refractive index of the material for the inorganic thin film 8 , i.e. silicon oxide is 1.7 or lower, so that the above-mentioned directional coupler can be produced. Thus, light emitted from the semiconductor laser 25' , controlled by the semiconductor laser driving circuit formed in the electronic circuit portion 24 , propagates through the optical waveguide portion 27 as indicated by an arrow in Figures 19A and 19B and is introduced into the optical coupling portion 28 . Thereafter, the light transmitted through the optical isolator portion 26 is output outside and introduced into an optical fiber 41 or the like. The present example shows the case where the semiconductor laser 25', the semiconductor laser driving circuit formed in the electronic circuit portion 24 , and the optical isolator portion 26 are integrated. Alternatively, a light emitting diode and an amplifier can be formed in place of the semiconductor laser 25' and the semiconductor driving circuit, respectively. These devices can be provided in a plurality of numbers. Furthermore, various kinds of methods can be applied for optical coupling in addition to the above-mentioned method. As described above, by integrating the electronic element, optical element, and magnetic device, the entire device can be miniaturized and optical alignment is facilitated. Example 12 Figure 20 shows the construction of still another hybrid magnetic structure 219 according to the present invention. The hybrid magnetic structure 219 has a supporting substrate 31 , a YIG magnetic single crystalline layer 2 , and an inorganic thin film 8 . The supporting substrate 31 is made of lithium niobate, lithium tantalate, etc., which allows light to pass therethrough and has an electro-optic effect. The inorganic thin film 8 is made of silicon oxide or silicon nitride. The inorganic thin film 8 is formed on the YIG magnetic single crystalline layer 2 by vacuum deposition, sputtering, CVD, etc. in the same way as in Example 8 . The YIG magnetic single crystalline layer 2 is bonded to the supporting substrate 31 through direct bonding in the same way as in Example 1 at an interface between the inorganic thin film 8 and the supporting substrate 31 . Even in the case where a light-transmitting substrate is used as the supporting substrate 31 , an optical isolator or a magnetostatic wave device can be produced by utilizing the construction of Example 7. Furthermore, by using a light-transmitting substrate having an electro-optic effect as the supporting substrate 31 , an integrated magnetic device can be produced in the same way as in Example 7. Example 13 A method for producing the hybrid magnetic structure 202 of Example 1 shown in Figure 2 will be described with reference to a flow chart of Figure 21 . First, the surface of the supporting substrate and that of the magnetic layer are flattened by grinding. The grinding is continued until a mirror finish can be obtained on the surfaces. Then, the surfaces to be bonded are cleaned with a detergent and various kinds of solvents (S1). The respective surfaces are subjected to a hydrophilic treatment by using a solution containing ammonia and hydrogen peroxide at a temperature in the range of 60°C to 70°C (S2). Thereafter, the surfaces subjected to the hydrophilic treatment are thoroughly washed with pure water. Then, the substrate and the layer are attached to each other so that the treated surfaces face each other, whereby the supporting substrate is directly bonded to the magnetic layer (S3). The bonded substrate and layer are heat-treated under this condition to increase the bonding strength (S4). When the bonded substrate and layer are heat-treated at a temperature in the range of 100°C to 800°C, the bonding strength is further increased. The temperature for heat treatment can be set depending upon the use of the hybrid magnetic structure 202 . It is noted that depending upon the case, the heat treatment step can be omitted. In the case where the temperature for heat treatment is high, the great difference in thermal expansion coefficient between the supporting substrate and the magnetic layer causes large thermal stress at the bonding interface. In order to reduce the thermal stress, it is required to appropriately determine the configuration of the substrate and the layer and the size thereof. When the bonded substrate and layer are heat-treated at higher temperatures, the thermal stress can be reduced by making the thickness and area of the magnetic layer smaller, and hence the bonding strength can be increased without delamination or damaging the bonding interface. The bonding strength is increased by several times, i.e., the bonding strength of tens of Kg/cm 2 can be obtained only by allowing the bonded substrate and layer to be subjected to heat treatment at 200°C for about one hour. The temperature for heat treatment may be equal to or lower than a temperature at which the supporting substrate and the magnetic layer change in quality. As described above, substrates and layers made of various kinds of materials can be bonded through direct bonding by appropriately setting a hydrophilic treatment method, a heat treatment temperature, a thermal expansion coefficient of substrates and layers to be bonded, and size of the substrates and layers. The hydrophilic treatment method is not limited to that described above. Alternatively, a known method for introducing hydroxyl groups into the surfaces of the substrates and the layers can be used. In the case where : garnet (represented by a general formula : A 3 B 5 O 12 ) such as YIG; materials obtained by partially replacing the constituting element of YIG by bismuth (Bi); materials obtained by partially replacing the constituting element of YIG by a rare-earth element; or ferrite (represented by a general formula : MO.Fe 2 O 3 , M is Mn, Fe, Co, Ni, Zn, Mg, etc.); are used as the magnetic layer, and magnetic substance such as garnet crystal (e.g., GGG); a material obtained by replacing the constituting element of GGG by another element; and ferrite, glass such as quartz glass and glass borosilicate; semiconductors such as Si, III-V group compound semiconductors such as GaAS or InP; and light-transmitting substances having an electro-optic effect such as lithium niobate or lithium tantalate are used as the supporting substrate, the direct bonding can be satisfactorily performed by the above-mentioned production method. In the case where the magnetic layer and the supporting substrate are made of the identical material or made of materials having almost the same thermal expansion coefficients, the bonded substrate and layer can be heat-treated at higher temperatures, and hence more satisfactory bonding strength can be obtained. Furthermore, in the case where glass is used for the supporting substrate, the thermal expansion coefficient thereof can be varied in a wide range, so that glass having a thermal expansion coefficient matched with that of the magnetic layer to be used can be utilized for the supporting substrate. The substrates to be used for the direct bonding are preferably single crystalline substrates which can easily provide flat and clean surfaces. The reason for this is that the unevenness of the surfaces of the substrates affect the yield of the direct bonding. According to the present example, the bonding interface can be obtained in the order of an atomic level without using an adhesive, so that a hybrid magnetic structure stable against the thermal change and mechanical vibration can be produced. Example 14 A method for producing the hybrid magnetic structure 213 of Example 8 shown in Figure 14 will be described with reference to a flow chart of Figure 22 . First, the surface of the supporting substrate and that of the magnetic layer are flattened by grinding. The grinding is continued until a mirror finish can be obtained on the surfaces. Then, the inorganic thin film is formed on at least one of the substrate or the layer to be bonded by sputtering, vacuum deposition, CVD, etc. (S11). As a material for the inorganic thin film, silicon oxide or silicon nitride is used. This material may be polycrystalline or amorphous. Then, the surface to be bonded of the substrate or the layer on which the inorganic thin film is not formed and the surface of the inorganic thin film are cleaned with a detergent and various kinds of solvents (S12). The respective surfaces are subjected to a hydrophilic treatment by using a solution containing ammonia and hydrogen peroxide at a temperature in the range of 60°C to 70°C (S13). Thereafter, the surfaces subjected to the hydrophilic treatment are thoroughly washed with pure water. Then, the substrate and the layer are attached to each other so that the treated surfaces face each other, whereby the supporting substrate is directly bonded to the magnetic layer in the same way as in Example 13 (S14). The bonded substrate and layer are heat-treated under this condition to increase the bonding strength (S15). When the bonded substrate and layer are heat-treated at a temperature in the range of 100°C to 800°C, the bonding strength is further increased. The effects obtained by the heat treatment are almost similar to those of Example 13. The bonding strength is increased by several times, i.e., the bonding strength of tens of Kg/cm 2 can be obtained only by allowing the bonded substrates to be subjected to heat treatment at 200°C for about one hour. The temperature for heat treatment may be equal to or lower than a temperature at which the supporting substrate and the magnetic layer change in quality. In Example 8, the case where the inorganic thin film is formed on the magnetic layer is described; however, even though the inorganic thin film is formed on the supporting substrate, the direct bonding can be performed in the same way. Furthermore, even though the inorganic thin films are formed on both, the substrate and the layer, the direct bonding can be performed in the same way. In any case, the function and performance of the resulting hybrid magnetic structures are almost the same. In the direct bonding formed by heat treatment at high temperatures, covalent bonds play a critical part. Therefore, when an inorganic insulating layer containing silicon oxide or nitride is used, covalent bonds can be easily formed to increase the bonding strength. In the case where garnet (represented by a general formula: A 3 B 5 O 12 ) such as YIG, materials obtained by partially replacing the constituting element of YIG by bismuth (Bi), materials obtained by partially replacing the constituting element of YIG by rare-earth element, or ferrite (represented by a general formula: MO•Fe 2 O 3 , M is Mn, Fe, Co, Ni, Zn, Mg, etc.) are used as the magnetic substrate, and a magnetic substance such as garnet crystal (e.g., GGG), a material obtained by replacing the constituting element of GGG by another element, and ferrite, glass such as quartz glass and glass borosilicate, semiconductors such as Si, III-V group compound semiconductors such as GaAs or InP, and light-transmitting substances having an electro-optic effect such as lithium niobate or lithium tantalate are used as the supporting substrate, the direct bonding can be satisfactorily performed by the above-mentioned production method. In the case where the magnetic layer and the supporting substrate are made of the identical material or made of materials having almost the same thermal expansion coefficients, the bonded substrates can be heat-treated at higher temperatures, and hence more satisfactory bonding strength can be obtained. Furthermore, in the case where glass is used for the supporting substrate, the thermal expansion coefficient thereof can be varied in a wide range, so that glass having a thermal expansion coefficient matched with that of the magnetic layer to be used can be utilized for the supporting substrate. The substrates to be used for the direct bonding are preferably single crystalline substrates which can easily provide flat and clean surfaces. The reason for this is that the unevenness of the surfaces of the substrates affect the yield of the direct bonding. Compared with the method of Example 13, the present example has the following advantages. The inorganic thin film works as a buffer layer for the stress generated at the interface of the direct bonding, so that the limitation to the difference in thermal expansion coefficient between the magnetic layer and the supporting substrate and the size thereof can be slightly alleviated. Because of this, the bonded substrate and layer can be heat-treated at higher temperatures; as a result, increased bonding strength can be obtained. Furthermore, even when some dust is present on the bonding interface, such dust is taken in the inorganic thin film while the direct bonding is strengthened by the heat treatment. Therefore, the production yield is enhanced. These advantages are remarkably obtained in the case where silicon oxide having lower rigidity than that of the magnetic single crystalline layer is used. According to the present example, the bonding interface can be obtained in the order of an atomic level without using an adhesive, so that a hybrid magnetic structure stable against the thermal change and mechanical vibration can be produced. The present example shows the application of the hybrid magnetic structures to particular devices. However, the present example is not limited thereto and can be applied to other devices such as a magnetic head. According to the present invention, a hybrid magnetic structure can be produced without using an adhesive such as an organic substance. This makes it possible to obtain a satisfactory parallel relationship between the bonded substrate and layer and to perform minute processing on the surface of the resulting hybrid magnetic structure with high precision. In addition, the hybrid magnetic structure thus obtained by using direct bonding is thermally, mechanically, and chemically stable. Furthermore, the degree of freedom for combining the materials for the supporting substrate and the magnetic layer is high, so that the hybrid magnetic structure suitable for its purpose can be readily produced. This results in the increase in the degree of freedom for designing an applied magnetic device such as an optical isolator and a magnetostatic wave device. Furthermore, according to the present invention, an integrated magnetic device, in which a magnetic device, electronic elements, and optical elements are integrally formed, can be obtained.

Claims: A hybrid magnetic structure (202 ; 213) comprising : a supporting substrate (1) or a supporting substrate (1) having an inorganic thin film (8) of SiO 2 or Si 3 Ni 4 on its contacting surface, a single crystalline magnetic layer (2) or a single crystalline magnetic layer (2) having an inorganic thin film (8) of SiO 2 or Si 3 Ni 4 on the contacting surface ; the substrate (1) and the layer (2) being covalently bonded with optional additional hydrogen bonding, resulting in either a substrate-layer bond structure or a substrate-thin film-layer bond structure. A hybrid magnetic structure (202 ; 213) according to claim 1, wherein the thickness of the inorganic thin film (8) between the magnetic layer (2) and the supporting substrate (1) directly bonded to each other, is 20 nm or less. A hybrid magnetic structure (202 ; 213) according to claim 1, wherein the material for the magnetic layer (2) is a garnet. A hybrid magnetic structure (202 ; 213) according to claim 3, wherein the material for the magnetic layer (2) is mainly yttrium-iron-garnet. A hybrid magnetic structure (202 ; 213) according to claim 1, wherein the supporting substrate (1) is made of a semiconductor material. A hybrid magnetic structure (202 ; 213) according to claim 5, wherein the semiconductor material is silicon. A hybrid magnetic structure (202 ; 213) according to claim 5, wherein the semiconductor material is a III-V group semiconductor material. A hybrid magnetic structure (202 ; 213) according to claim 1, wherein the material for the supporting substrate (1) is glass. A hybrid magnetic structure (202 ; 213) according to claim 8, wherein the thermal expansion coefficient of the glass is substantially the same as a thermal expansion coefficient of the magnetic structure (2). A hybrid magnetic structure (202 ; 213) according to claim 1, wherein the supporting substrate (1) is a light-transmitting substrate having an electro-optic effect. A hybrid magnetic structure (202 ; 213) according to claim 1, wherein the material for the supporting substrate (1) is magnetic. A hybrid magnetic structure (202 ; 213) according to claim 1, wherein the material for the magnetic layer (2) is the same as a material for the supporting substrate (1). A method for producing a hybrid magnetic structure according to one of claims 1 to 12, comprising the steps of : cleaning a surface of the magnetic layer (2) to be bonded and a surface of the supporting substrate (1) to be bonded ; allowing the cleaned surfaces to be subjected to a hydrophilic treatment ; attaching the surfaces, which are subjected to the hydrophilic treatment, to each other to directly bond the magnetic layer (2) to the supporting substrate (1), and heat treating the structure at a temperature between 100°C and 800°C. A method for producing a hybrid magnetic structure according to one of claims 1 to 12, comprising the steps of : forming the inorganic thin film (8) on at least one surface to be bonded of the magnetic layer (2) and the supporting substrate (1) ; cleaning a surface of the inorganic thin film (8) and the surface to be bonded on which the inorganic thin film (8) is not formed ; allowing the cleaned surface of the inorganic thin film (8) and the surface to be bonded on which the inorganic thin film (8) is not formed to be subjected to a hydrophilic treatment ; attaching the surfaces, which are subjected to the hydrophilic treatment, to each other to directly bond the magnetic layer (2) to the supporting substrate (1), and heat treating the structure between 100°C and 800°C. A magnetic wave device (206 ; 215) comprising a hybrid magnetic structure according to one of claims 1 to 12, wherein an electrode (5) for exciting a magnetostatic wave is provided on the magnetic layer (2). A magnetic device (210 ; 218) comprising a hybrid magnetic structure according to one of claims 1 to 12, wherein the magnetic layer (2) has a magneto-optic effect and an optical waveguide is formed on the magnetic layer (2). A magnetic device (210 ; 218) comprising a hybrid magnetic structure according to one of claims 1 to 12, wherein the magnetic layer (2) has a magneto-optic effect and the magnetic layer (2) has a function as an optical isolator (26). A magnetic device (210 ; 218) comprising a hybrid magnetic structure according to one of claims 1 to 12, wherein the supporting substrate (1) is a light-transmitting substrate having an electro-optic effect and an optical device is formed on the light-transmitting substrate. An integrated magnetic device (210 ; 218) comprising a hybrid magnetic structure according to one of claims 1 to 12, wherein the supporting substrate (1) is made of a semiconductor material and at least one element selected from the group consisting of an electronic element and an optical element is formed on the supporting substrate (1). A hybrid magnetic structure (202 ; 213) according to one of claims 1 to 12, wherein said hydrogen bond is formed between hydroxyl groups, and the covalent bond is obtained by transforming the hydrogen bond and includes an oxygen atom. A method for producing a hybrid magnetic structure according to one of claims 13 or 14, further comprising the step of heating said structure to a temperature in the range of 100°C to 500°C.

Inventors: EDA KAZUO, EDA, KAZUO
Applicants: MATSUSHITA ELECTRIC IND CO LTD, MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
Application year: 1994
Main classification: H03H2
IPC codes: H01L21, H01F10, H03H2, G02F1, G02B6